Effects of Different Cultivation Conditions on the Establishment of an Efficient Regeneration System for Soapwort

To optimize tissue culture rapid propagation technology for soapwort, young stems, leaves, and leaf axils were used as experimental materials. The MS medium supplemented with 6-BA（2.0 mg·L⁻¹）+ 2,4-D（0.5 mg·L⁻¹）+ 10% coconut milk was employed to identify the optimal explant sites and sterilization duration. Further, an L₉(3⁴) orthogonal test was conducted using MS, 1/2MS, and WPM as base media. By varying concentrations of 6-BA and NAA and adjusting sterile water-holding times, the optimal medium for axillary explant growth and the best formulation for inducing green callus were identified. Growth performance of soapwort tissue-cultured seedlings under different media and hormone combinations was also compared. Results indicate: The optimal explant site for soapwort is the leaf axil, with an optimal sterilization time of 8 min yielding the highest survival rate of 58.58%. The optimal growth medium combination for leaf axils was 1/2 MS + 6-BA（0.5 mg·L⁻¹）+ NAA（0.05 mg·L⁻¹）+ sterile water control for 3 days, yielding the highest callus formation rate of 20%, surpassing other treatments. The optimal medium combination for inducing green callus from leaf axils was WPM + 6-BA（0.1 mg·L⁻¹）+ NAA（0.2 mg·L⁻¹）+ sterile water control for 3 days, yielding a 60% callus formation rate. These findings provide a reference for establishing an efficient regeneration system and tissue culture techniques for soapwort, while also offering high-quality seedlings and technical guidance for its industrialized propagation.